Radio communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such radio communication networks support communications for multiple UEs by sharing the available network resources. The above-mentioned UEs may sometimes be referred to as wireless communication devices, communication devices, mobile terminals, terminals, user terminals (UTs), wireless terminals, wireless transmit/receive units (WTRUs), etc. One example of a radio communication network is the Universal Mobile Telecommunications System (UMTS), a third generation (3G) technology standardized by the 3rd Generation Partnership Project (3GPP). UMTS includes a definition for a Radio Access Network (RAN), referred to as UMTS Terrestrial Radio Access Network (UTRAN). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, supports various air interface standards, such as Wideband Code Division Multiple Access (WCDMA), Time Division Code Division Multiple Access (TDCDMA), and Time Division Synchronous Code Division Multiple Access (TDSCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks. As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications. For example, third-generation UMTS based on WCDMA has been deployed in many places of the world. To ensure that this system remains competitive in the future, 3GPP began a project to define the long-term evolution of UMTS cellular technology. The specifications related to this effort are formally known as Evolved UMTS Terrestrial Radio Access (E-UTRA) and Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), but are more commonly referred to by the name Long Term Evolution (LTE). The complete network is called Evolved packet System (EPS).
UEs and the underlying radio communication networks are generally configured to support and facilitate emergency call handling, e.g. 911 calls and the like. In many countries (e.g. the U.S.) it is mandatory that the UE reports its location upon the subscriber (e.g. the user) establishes an emergency call. One example procedure is known from the 3GPP Technical Specification TS 23.271, V.11.2.0, section 9.1.5A. FIG. 9.4A of this section is reproduced in FIG. 1 and illustrates an example of UE location reporting during an emergency call establishment procedure. In other countries, the location of the UE may instead be requested at any time during the emergency call establishment. One example procedure is known from the same technical specification, section 9.1.5. FIG. 9.4 of this section is reproduced in FIG. 2 and illustrates an example of UE location reporting during an emergency call establishment procedure according to section 9.1.5 of the 3GPP TS 23.271, V.11.2.0. As is well-known among those persons skilled in the art, there exist various methods for establishing, or otherwise determining, the location (i.e. the position) of the UE. For example, chapter 32 of the reference book “Positioning in LTE, Handbook of Position Location, Theory Practice and Advances: A Handbook for Engineers and Academics” written by Ari Kangas, Iana Siomina, and Torbjörn Wigren and published by IEEE Press & Wiley in 2012, discloses some positioning methods.
Generally, the location of the UE will be determined and reported each time the subscriber (e.g. the user) establishes an emergency call. In general, the reporting of the location of the UE delays the emergency call establishment procedure to a certain degree. Also, the location determination (i.e. the positioning) of the UE per se causes a delay to the emergency call establishment procedure. The exact delay of the location determination may vary depending on which positioning method that is actually used.
To sum up, the UE location determination and reporting causes a delay to the emergency call handling. This delay becomes even more serious in situations where an emergency call is dropped, e.g. because of bad radio conditions. In such situation, the subscriber will generally have to perform a new emergency call. Performing a second emergency call following the first emergency call may be perceived as very inconvenient for the subscriber, since a subscriber making an emergency call generally wishes to get connected to the emergency center quickly and without any unnecessary delay.
In an attempt to improve the existing art, the U.S. Pat. No. 6,240,285 B1 suggests alternative carrier selection on repeat emergency calls. According to U.S. Pat. No. 6,240,285 B1, wireless telephone networks and other mobile radio services networks provide 911 or similar emergency calling services between mobile stations and a public safety answering point (PSAP). In emergency situations, the caller often will not be satisfied with the quality of the link to the PSAP, for any of a variety of subjective reasons. In such a case, the caller ends the first emergency call and initiates another emergency call. In accordance with U.S. Pat. No. 6,240,285 B1, if the caller initiates the second emergency call within a predetermined interval from the first call, the mobile station will select an alternate operating system of the network for the second call. For example, if the first call utilized an A-side cellular carrier, the handset will select a B-side or PCS carrier for the second call. The handset also may select a different technology, e.g. analog instead of the normally preferred digital, for the second emergency call. The expectation according to U.S. Pat. No. 6,240,285 B1 is thus that conditions will be different on the alternate operating system and provide a quality of service that the emergency caller subjectively finds more acceptable.